login - sign on
login [ -p ] [ username ]
The login command is used when a user initially signs on, or it may be used at any time to
change from one user to another. The latter case is the one summarized above and
described here. See "How to Get Started" for how to dial up initially.
If login is invoked without an argument, it asks for a user name, and, if appropriate, a
password. Echoing is turned off (if possible) during the typing of the password, so it
will not appear on the written record of the session.
After a successful login, accounting files are updated and the user is informed of the
existence of mail. The message of the day is printed, as is the time of his last login.
Both are suppressed if he has a ".hushlogin" file in his home directory; this is mostly
used to make life easier for non-human users, such as uucp.
Login initializes the user and group IDs and the working directory, then executes a com-
mand interpreter (usually csh(1)) according to specifications found in a password file.
Argument 0 of the command interpreter is the name of the command interpreter with a lead-
ing dash ("-").
Login also modifies the environment environ(7) with information specifying home directory,
command interpreter, terminal type (if available) and user name. The `-p' argument causes
the remainder of the environment to be preserved, otherwise any previous environment is
If the file /etc/nologin exists, login prints its contents on the user's terminal and
exits. This is used by shutdown(8) to stop users logging in when the system is about to go
Login is recognized by sh(1) and csh(1) and executed directly (without forking).
/etc/passwd password file
/etc/nologin stops logins
.hushlogin makes login quieter
init(8), getty(8), mail(1), passwd(1), passwd(5), environ(7), shutdown(8), rlogin(1c)
"Login incorrect," if the name or the password is bad.
"No Shell", "cannot open password file", "no directory": consult a programming counselor.
An undocumented option, -r is used by the remote login server, rlogind(8C) to force login
to enter into an initial connection protocol. -h is used by telnetd(8C) and other servers
to list the host from which the connection was received.
4th Berkeley Distribution November 27, 1996 LOGIN(1)